1. Technical Field
The present invention relates to an illumination device such as an organic EL illumination device for use as a backlight or the like.
2. Related Art
These days, a light emission device (illumination device) that is provided with organic EL elements is used as a backlight for a liquid crystal display screen of lighting fixture, electronic information equipment, and the like. Since a light emission device that is provided with organic EL elements is self-luminous, it offers a wide angle of view and excellent visibility. In addition, since the element is a thin-film perfect solid-state component, space-saving design can be achieved. Because of these features, it is attracting attention from the industry as a light emission source. An example of such a light emission device is disclosed in JP-A-2007-26932.
In an organic EL light emission device according to related art, unevenness of brightness occurs as a difference between the brightness of a light emission area near a power-receiving part of a positive electrode and the brightness of a light emission area away from the power-receiving part. This is because, since the resistance of a transparent electrode layer used for the positive electrode is large, a voltage drop is relatively large at an area that is relatively distant from the positive-electrode-side power-receiving part, which causes a decrease in light-emission brightness. To address such a problem, a technique of supplying power to a positive electrode from a plurality of power-receiving parts via auxiliary wiring is disclosed in JP-A-2007-26932.
However, a light emission device disclosed in JP-A-2007-26932 has the following disadvantages. Since positive electrode auxiliary wiring is provided over a positive electrode in an organic EL light emission area and the periphery of the organic EL light emission area, the layout of the positive electrode and the positive electrode auxiliary wiring is complex, resulting in a decrease in productivity. Material cost increases for forming a metal electrode layer. Energy inputted to a deposition apparatus at the time of manufacturing increases. Another production inefficiency is longer manufacturing time. In other words, it is difficult to achieve both uniform light emission throughout the entire light emission area and high efficiency in the manufacturing of an organic EL illumination device.